Changeset a78cdcd in mainline

Timestamp:

2019-05-19T14:56:33Z (5 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

967e7a1

Parents:

aeeaf0f

git-author:

Jakub Jermar <jakub@…> (2019-05-19 14:50:47)

git-committer:

Jakub Jermar <jakub@…> (2019-05-19 14:56:33)

Message:

Avoid division by zero when time difference is 0

Sometimes, especially under emulation, the CPU is much faster than the
PIT so that the computed time difference is zero. Adjust to the nearest
possible non-zero value to avoid division by zero.

File:

• kernel/arch/ia32/src/drivers/i8254.c (modified) (1 diff)

kernel/arch/ia32/src/drivers/i8254.c

@@ -143 +143 @@
         o2 |= pio_read_8(CLK_PORT1) << 8;
 
+        uint32_t delta = (t1 - t2) - (o1 - o2);
+        if (!delta)
+                delta = 1;
+
         CPU->delay_loop_const =
-            ((MAGIC_NUMBER * LOOPS) / 1000) / ((t1 - t2) - (o1 - o2)) +
-            (((MAGIC_NUMBER * LOOPS) / 1000) % ((t1 - t2) - (o1 - o2)) ? 1 : 0);
+            ((MAGIC_NUMBER * LOOPS) / 1000) / delta +
+            (((MAGIC_NUMBER * LOOPS) / 1000) % delta ? 1 : 0);
 
         uint64_t clk1 = get_cycle();